1. Field of the Invention
The present invention relates to a method of attaching or detaching a servo tool unit of servo motor drive type mounted at the forward end of an arm of a robot and a robot controller for carrying out the method.
2. Description of the Related Art
The tool unit mounted at the forward end of the robot arm includes a servo tool unit of servo motor drive type such as a welding gun and a hand. Such a servo tool unit is controlled together with the robot by a robot controller. When the servo tool unit mounted on the tool mounting portion provided at the forward end of the robot arm is changed automatically, the mechanical detachment and attachment of the servo tool unit from/to the tool mounting portion and the software processing for electrically disconnecting and connecting a motor are required. In the prior art, the mechanical detachment of the servo tool unit and the software process involved with the electrical disconnection of the motor including the processes of invalidating the disconnection error of a power line and a signal line, confirming the motor stop and invalidating the servo parameters are executed at the position where the servo tool unit is mechanically detached. Similarly, the mechanical attachment of the servo tool unit and the software process involved with the electrical connection including the processes of validating the disconnection error of the power line and the signal line, confirming the motor start and validating the servo parameters are executed at the position where the servo tool unit is mechanically attached.
In the conventional servo tool unit detachment method executed when automatically changing the servo tool unit, the mechanical detachment and the software process for the electrical disconnection of the motor are executed at the same position. This poses the problem of a long down time of the robot at the time of detaching the servo tool unit. Similarly, in the conventional servo tool unit attachment method, the mechanical attachment and the software process for the electrical connection of the motor are executed at the same position, and therefore the down time of the robot is long at the time of attaching the servo tool unit. As a result, the problem is posed that the proportion of time during which the robot is actually used for production is reduced, resulting in a deteriorated working efficiency.